fairypp 发表于 2013-8-26 06:19
从结构上说 scientists believe that X
that Y
OG上有讲,可以 ...
意思是believe后跟了两个从句
1. (That) the evident is a result
2. (That) our ancestors suffered an event
这两个从句,用---连接。并且从句2 带有一个修饰语modifier:(that) reduced numbers and variation 来修饰event